wolffd@0: function marginal = marginal_nodes(engine, query, add_ev)
wolffd@0: % MARGINAL_NODES Compute the marginal on the specified query nodes (cond_gauss)
wolffd@0: % marginal = marginal_nodes(engine, query, add_ev)
wolffd@0: %
wolffd@0: % 'query' must be a singleton set
wolffd@0: % add_ev is an optional argument; if 1, we will "inflate" the marginal of observed nodes
wolffd@0: % to their original size, adding 0s to the positions which contradict the evidence
wolffd@0: 
wolffd@0: if nargin < 3, add_ev = 0; end
wolffd@0: 
wolffd@0: if length(query) ~= 1
wolffd@0:   error('cond_gauss_inf_engine can only handle marginal queries on single nodes')
wolffd@0: end
wolffd@0: j = query;
wolffd@0: bnet = bnet_from_engine(engine);
wolffd@0: 
wolffd@0: if myismember(j, bnet.cnodes)
wolffd@0:   if ~myismember(j, engine.onodes)
wolffd@0:     [m, C] = collapse_mog(engine.mu{j}, engine.Sigma{j}, engine.T);    
wolffd@0:     marginal.mu = m;
wolffd@0:     marginal.Sigma = C;
wolffd@0:     marginal.T = 1.0; % single mixture component
wolffd@0:   else
wolffd@0:     marginal.mu = engine.evidence{j};
wolffd@0:     k = bnet.node_sizes(j);
wolffd@0:     marginal.Sigma = zeros(k,k);
wolffd@0:     marginal.T = 1.0; % since P(E|E)=1
wolffd@0:   end
wolffd@0: else
wolffd@0:   marginal = pot_to_marginal(marginalize_pot(engine.joint_dmarginal, j));
wolffd@0:   if add_ev
wolffd@0:     marginal = add_ev_to_dmarginal(marginal, engine.evidence, bnet.node_sizes);
wolffd@0:   end
wolffd@0: end
wolffd@0: 
wolffd@0: marginal.domain = query;